There is an increasing demand for very high-speed analog-to-digital converters (ADCs) in wireless communication systems. Such high-speed ADCs require the use of core thin-oxide devices in nanometer-scale technologies to achieve the desired sampling frequencies. The core thin-oxide devices are sensitive to overvoltage. Typically, the ADCs are interfaced with external low noise amplifiers (LNAs) or radio frequency (RF) variable gain amplifiers (VGAs). The LNAs/RF VGAs supply signals that can exceed the reliability limits of the ADC, resulting in potential damage to the core thin-oxide devices.
One technique to protect against overvoltage is to use external Schottky diodes to prevent the voltage from rising about the reliability levels. Those additional devices, however, reduce the maximum achievable bandwidth, introduce distortion, and increase the bill-of-materials (BOM) and other associated costs. It is therefore desirable to provide overvoltage protection without the use of such external devices.